Chronic hepatitis C (HCV) infections are present in approximately 71 million individuals throughout the world. Among this population, 8% of global infections are present in people who inject drugs (PWID). Despite these statistics, many clinicians still have reservations about offering direct-acting antiviral (DAA) therapy to individuals with HCV infections who use injectable drugs or are currently receiving opioid substitution therapy.

In a study published in The Lancet Gastroenterology and Hepatology, investigators from the Kirby Institute found that PWID or individuals currently receiving opioid substitution therapy responded favorably to DAA therapy with sofosbuvir and velpatasvir. The study provides the “strongest evidence-base to date” to support the removal of restrictions to accessing therapy for HCV based on recent drug use.

“Across almost 40 studies worldwide, involving more than 3,500 people with recent or ongoing drug use, hepatitis C was cured in almost 9 out of 10 people," Behzad Hajarizadeh, PhD, from the Viral Hepatitis Clinical Research Program at the Kirby Institute, and lead author on the study, said in a recent statement.

Prior to evaluating the effectiveness of sofosbuvir and velpatasvir for HCV infections in PWID, the investigators conducted a literature review of past research. The data showed that use of DAA therapy among PWID and people receiving opioid substitution therapy are similar to individuals with HCV who do not use or have a history of injection drug use, according to the report; however, there were no international studies evaluating DAA treatment in people who have injected drugs in the past 6 months.

In the SIMPLIFY phase 4 study, investigators enrolled 103 participants from 19 study sites across 7 countries. The participants were required to have used injection drugs in the past 6 months and have a chronic HCV genotype 1-6 infection.

The participant population was made up of 36 participants with genotype 1, 5 with genotype 2, 60 with genotype 3, and 2 with genotype 4. Additionally, 61 participants were receiving opioid substitution therapy, 76 individuals reported injecting drugs in the past month, and 27 participants reported daily injection drug use.

Each participant received oral sofosbuvir (400 mg) and velpatasvir (100 mg) once-daily for the duration of 12 weeks. Therapy was given in 1-week electronic blister packs in order to record the time and date of each dose.

Results indicate that 100 of 103 participants completed treatment; 2 participants were lost to follow-up and 1 participant died of a drug overdose. Of the 100 individuals who completed the course of treatment, 97 individuals achieved sustained viral response (SVR)12, defined as HCV RNA <12 IU/mL. No virological failures were observed.

Treatment-related adverse events were observed in 48 patients; one grade 3 event was reported, but grade 4 events were not observed. Serious adverse events were reported in 7 patients, with only 1 event determined to possibly be related to treatment—a case of rhabdomyolysis that was later resolved.

The evidence provided from this investigaton indicates that HCV treatment should be offered to PWID regardless of current drug use, according to the investigators.

“These data provide convincing data to support DAA therapy in people who inject drugs, addressing concerns from some HCV providers that response to therapy is lower in people with ongoing drug use,”Jason Grebely, PhD, associate professor at the Kirby Institute and President of the International Network of Hepatitis in Substance Users, and an author of the study told Contagion®. “These data are critical for informing clinical management of HCV among people who use drugs."

Dr. Grebley also indicated that future research should focus on enhancing HCV testing as well as access to care and treatment among PWID along with expanding the scope of research to determine the best methods to enhance linkage to care in this population.
Updated: 9/25/18 at 8:45 AM EDT to reflect quotes from Dr. Jason Grebely

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